<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .bg {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            overflow: hidden;
            background: linear-gradient(to bottom right, #50A3A2, #53E3A6);
        }

        li {
            position: absolute;
            top: -100px;
            width: 40px;
            height: 40px;
            text-align: center;
            line-height: 40px;
            background-color: rgba(255, 255, 255, 0.15);
            list-style: none;
            animation: square 15s infinite;
            transition-timing-function: linear;
            border-radius: 50%;
        }

        li:nth-child(1) {
            left: 8%;
        }

        li:nth-child(2) {
            left: 12%;
            animation-delay: 2s;
            animation-duration: 7s;
        }

        li:nth-child(3) {
            left: 25%;
            animation-delay: 4s;
        }

        li:nth-child(4) {
            left: 40%;
            animation-duration: 8s;
            background-color: rgba(255, 255, 255, 0.3);
        }

        li:nth-child(5) {
            left: 70%;

        }

        li:nth-child(6) {
            left: 80%;
            animation-delay: 3s;
            background-color: rgba(255, 255, 255, .2);
        }

        li:nth-child(7) {
            left: 32%;
        }

        li:nth-child(8) {
            left: 55%;
            animation-delay: 4s;
            animation-duration: 15s;

        }

        li:nth-child(9) {
            left: 25%;
            animation-delay: 2s;
            animation-duration: 15s;
            background-color: rgba(255, 255, 255, 0.3);
        }

        li:nth-child(10) {
            left: 85%;
            animation-delay: 5s;
        }

        @keyframes square {
            0% {
                opacity: 0.5;
                transform: translateY(0px) rotate(45deg);
            }
            25% {
                opacity: 0.75;
                transform: translateY(400px) rotate(90deg);
            }
            50% {
                opacity: 1;
                transform: translateY(600px) rotate(135deg);
            }
            100% {
                opacity: 0;
                transform: translateY(1000px) rotate(180deg);
            }
        }

    </style>
</head>
<body>
<ul class="bg">
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
    <li>7</li>
    <li>8</li>
    <li>9</li>
    <li>10</li>
</ul>

</body>
</html>